Prominent lawmaker Alaeddin Boroujerdi said Iranian security experts discovered the explosives and removed them before detonation, adding that authorities believe the booby-trapped equipment was sold to derail uranium enrichment efforts.

"The equipment was supposed to explode after being put to work, in order to dismantle all our systems," he said. "But the wisdom of our experts thwarted the enemy conspiracy."

Siemens denied the charge and said its nuclear division has had no business with Iran since the 1979 revolution that led to its current clerical state.

"Siemens rejects the allegations and stresses that we have no business ties to the Iranian nuclear program," spokesman for the Munich-based company Alexander Machowetz said.

Boroujerdi, who heads the parliamentary security committee, alleged that the explosives were implanted at a Siemens factory and demanded the company take responsibility.

Any sale of nuclear equipment to Iran is banned under U.N. sanctions, raising the possibility that if it indeed has some, it may have been acquired through third parties. Boroujerdi did not say when or how Iran obtained Siemens equipment. Despite a wide array of international sanctions, Germany remains one of Iran's most important trading partners.

The U.S. and its allies suspect Iran's nuclear work is aimed at producing weapons. Iran says it only wants to enrich uranium for peaceful purposes, and asserts it has been the target of a concerted campaign by Israel, the U.S. and their allies to undermine its nuclear efforts through covert operations.

Some Iranian officials have also suggested in the past that specific European companies may have sold faulty equipment to Iran with the knowledge of American intelligence agencies and their own governments, since the sales would have harmed, rather than helped, the country's nuclear program.

According to Iran, the alleged campaign has included the abduction of scientists, the sale of faulty equipment and the planting of a destructive computer worm known as Stuxnet, which briefly brought Iran's uranium enrichment activity to a halt in 2010.

Iran's nuclear chief, Fereidoun Abbasi, said Monday that separate attacks on Iran's centrifuges — through tiny explosives meant to disable key parts of the machines — were discovered before the blasts could go off on timers.

Abbasi also told the U.N. nuclear agency in Vienna that "terrorists and saboteurs" might have infiltrated the International Atomic Energy Agency, after the watchdog's inspectors arrived at the Fordo underground enrichment facility shortly after power lines were blown up through sabotage on Aug. 17.

Iran has repeatedly accused the IAEA of sending spies in the guise of inspectors to collect information about its nuclear activities, pointing to alleged leaks of information by inspectors to U.S. and other officials.

Five nuclear scientists and researchers have been killed in Iran since 2010. Tehran blames the deaths on Israel's Mossad spy agency as well as the CIA and Britain's MI-6. Washington and London have denied any roles. Israel has not commented.